This invention relates in general to highway traffic control systems, and in particular relates to barriers which form traffic lane dividers.
Traffic control systems have previously been provided in which lane dividers or barriers have been mounted for transverse movement to vary the number of lanes in the different traffic streams. One system which has been proposed is that disclosed in the U.S. Pat. to Curtis No. 2,143,433 in which a barrier is mounted for transverse movement over an elevated highway by means of a single motor driving a common shaft which in turn drives cables connected with carriages upon which the barrier is mounted. Another prior art system is that of the Mahoney U.S. Pat. No. 3,391,620 in which the barrier is moved transversely of the roadway by means of a drive motor which is carried by the barrier and engages a flexible belt, the ends of which are trained along and affixed to opposite ends of a transverse groove formed in the roadway.
Moveable barrier systems of the type described have a number of limitations and have not been adopted in practice. In many cases it is desirable to divide the lanes of traffic in a manner which provides a transition zone where the divider barrier follows a curved or slanted path so that the flow of traffic can either spread out or neck down, such as at a toll plaza. The moveable barrier systems which have heretofore been proposed have not been adaptable to providing a system in which the barrier can change in such a transition zone.
It would be desirable to provide a moveable barrier system which is more simple and inexpensive in design and construction as compared to prior barrier systems, and furthermore which is easier to operate and maintain. Such a barrier system must also be capable of absorbing severe shock forces, such as by collision from a vehicle, and the prior art barrier systems are limited in their shock force absorbing capabilities. It would therefore be desirable to provide a moveable barrier system which is not only simple in its mode of operation but which can absorb high shock forces without damage.